載卵壓力和聚集效應對於大頭金蠅產卵行為的影響

法醫昆蟲學利用屍體上的麗蠅幼蟲來推估人類或動物的最小死後間隔時間（minimum post-mortem interval, minPMI）。產卵行為會直接影響幼蟲表現，進而影響死後間隔時間的推算。本研究以大頭金蠅（Chrysomya megacephala（Fabricius））為材料，探討載卵壓力和聚集效應對於大頭金蠅的產卵行為影響，試驗分成四個部分。首先從取得正常麗蠅的攜卵量，再對不同數量的共域雌蟲測試是否影響產卵量，之後給予連續產卵刺激以進行生殖週期測試。最後在排除聚集效應的影響下，將單隻交配過雌蟲給予連續產卵刺激，以日齡作為載卵壓力的量化指標測試雌蟲反應。在生理攜卵量部分，平均每隻雌蟲的攜卵量為263.4±36.4個。共域雌蟲數量測試結果為平均產卵量會隨數量增加而提高，數量達5隻以上則沒有顯著差異。在連續產卵刺激的生殖週期測試，發現有三個週期，各週期每隻雌蟲的平均產卵量分別為278.9±48.1、258.9±36.7及92.7±53.0顆，產卵間隔平均9.82±1.03天。單隻雌蟲產卵測試的結果則是一半以上的組別，會在持續刺激下超過20天以上才出現產卵行為，結果顯示不論是否出現產卵行為的單隻雌蟲，在體內的殘存卵量皆占多數。總結來說，共域雌蟲的數量會影響產卵表現，而單隻雌蟲試驗的結果可能因載卵壓力的影響不及聚集效應來的顯著，造成未產出的卵占多數。

關鍵字

大頭金蠅；生殖週期；載卵壓力；產卵行為；法醫昆蟲學

並列摘要

In forensic entomology, the thermo-histories of necrophagous blow fly maggots are used to estimate the minimum postmortem interval (minPMI). The oviposition behavior will directly influence the on-going larval performance, which affects minPMI estimation. In this study, we used Chrysomya megacephala (Fabricius) to test egg load and gregarious effects on ovipositon behavior. Our study was divided into four parts. The first one was the dissection of the ovaries of mature female adults to know their egg number. The second part involved determing if different accompanying female number will affect their egg number. The third part, we gave the flies continuous oviposition stimulus to find their reproductive cycles. On the last part, continunous oviposition stimulus was applied to measure the behavior of a mated single female, using fly age as a strength index for egg load and recorded the oviposition behavior. Results obtained by the ovary dissection indicated the average egg number in a female are 263.4 ± 36.4. Results from the second experiment revealed that as the accompanying female number increases, the average egg numbers laid also increased; but there was no significant difference once the accompying female number increases over five. Continuous oviposition stimulus revealed that there are three reproductive cycles. The average egg number per female for each cycle are 278.9 ± 48.1, 258.9 ± 36.7 and 92.7 ± 53.0, respectively; with a time gap of 9.82 ± 1.03 days in between. In the third experiment, more than half of those single females oviposited after 20 days; ovary dissection revealed that the egg numbers laid are significantly lower than the residual ones in the ovary. Our results indicated the number of accompanying females affects oviposition behavior, and the single female behavior is more strongly affected by the gregarious effect than by the egg load, which causing infrequent oviposition behavior.

並列關鍵字

Chrysomya megacephala ； Reproductive Cycle ； Egg Load ； Oviposition Behavior ； Forensic Entomology

參考文獻

Liao CS: Effects of early decomposition time on blow fly (Diptera: Calliphoridae) oviposition [Dissertation]. Taipei, Taiwan: National Taiwan University, 2016. 58p. doi:10.6342/NTU201600446

Yang ST: Taxonomy of blow flies in Taiwan and reproductive behavior of Chrysomya megacephala (Diptera: Calliphoridae) [Dissertation]. Taipei, Taiwan: National Taiwan University. 207p. doi:10.6342/NTU.2014.02896

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載卵壓力和聚集效應對於大頭金蠅產卵行為的影響

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